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Old 07-26-2020, 11:37 PM   #1
Al
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Fuel tank equalizing

Okay, to the forum,
I require the thinking on a fluid transfer situation. First, I have not visually reviewed the situation, only have had it transmitted to me verbally. I will attempt to pass on that vision for consideration by those who possess the mathematical or science level to take a shot at confirmation on the solution as I view it currently.

The boat is a commercial troller. The fuel tanks are of equal gallonage and size. The return line is to a single tank. There is no equalizer line between the tanks. On the tanks each are a drain valve The engine fuel system draws off both tanks.

.
The issue: When the boat was fishing with full fuel tanks, unknowing to the new owner, the return line was and did overfill the tank it is dedicated to.

He did shut off the non-return tank and drew down the tank and completed his trip (Initial fishing adventure for the lad and the boat)
Having to return to his day job in the 'Lower 48' left the boat here with the remaining ice onboard to milt and be discharged by the auto builge pump, which it did. However, during the fishing and icing of the catch, he favored the side opposit the fuel return line tank with shifting ice,which resulted in the boat taking on a list tied to the present mooring as it was pumped overboard.

It is this list that I am being asked to address in terms of leveling the boat. The young fellow is a engineer by degree so it is a bit hard for this highschool grad to get his arms around a meaningful plan in opposition.
His solution is to install a transfer pump at the drain outlet on the heavy tank and transfer to the light tank and install this apparatus to flow both ways between the two tanks as a permeant fix.

I differ on this due to the human error factor. Like the times I pull the manual buildge pump on periodically to clear any bilge water and forget to turn it off. I picture the same with any pump in the fuel line having the same results. I have suggested that he install a heavy duty flex fuel quality line between the two drains with valves as required and allow the tanks to seek their own level over time. His rebuttal and cause for this post, is that the heavy tank will not drain uphill, so to speak, forcing the light tank to rise, That the heavy tank being lower by the list, will allow the light tank to continue draining into the heavy tank causing further list. On one hand I accept his prims, on the other I have always been of the thought that fluis will seek its own level and the weight of the heavy tank fuel will overcome the light tank and eventually produce two level tanks.
In the meanwhile, I am proceeding tomorrow, to stick the tanks for the owner. I do not know at this time the degree of the list but it is not so sever as to be a safety concern of any measure.
What say you sailors?
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Old 07-27-2020, 03:33 AM   #2
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An equalizer line between the fuel tanks will only work if the rest of the boat is equally weighted. If something else is causing the boat to list, the equalizer line will only make it worse.

Install the transfer pump with a timer.
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Old 07-27-2020, 05:45 AM   #3
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Quote:
Originally Posted by AusCan View Post
An equalizer line between the fuel tanks will only work if the rest of the boat is equally weighted. If something else is causing the boat to list, the equalizer line will only make it worse.

Install the transfer pump with a timer.
From experience, AusCan speaketh the truth. Will indeed make it worse unless the boat is otherwise balanced, which is unlikely. Either move ballast or move fuel. Neither will do so without manual intervention.
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Old 07-27-2020, 06:41 AM   #4
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Quote:
Originally Posted by AusCan View Post
An equalizer line between the fuel tanks will only work if the rest of the boat is equally weighted. If something else is causing the boat to list, the equalizer line will only make it worse.

Install the transfer pump with a timer.
Yup, the simple, common and easily controlled approach.
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Old 07-27-2020, 12:12 PM   #5
Al
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Thanks guys, Will advise the young fellow. I appriciate your remarks which reflect the better of this forum's ability to assist/teach/for the betterment of boating.

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